From: Chris Taylor (email@example.com)
Date: Fri 28 Oct 2005 - 09:28:22 GMT
> But of course most speciation now is in fact thought to occur through
> random variation and random fixation rather than by selection as Darwin
> thought. There's good reason to think that some speciation is due to
> selection, but not much. I worry that we think only that Darwinian
> evolution is about selection (natural or sexual), when in fact another
> really deep aspect of his view is common descent, and this is not tied
> now to selection.
Selection has _no role_ in the generation of species the
majority of the time? Are you just purely talking about
permanent absolute allopatry / completely discrete allochrony or
whatever equivalent you care to pick?
Elephants and fleas will never successfully mate (having
diverged somewhat); but where this matters (i.e. in recent
speciation events, where those species ranges [or whatever]
overlap) selection is key in ensuring that hybrids are (1)
demonstrably crap and that (2) parents who find a way to avoid
sinking their genes into such crappy hybrids propagate more of
those genes forwards to subsequent generations..?
Random variation and fixation is _not good_ at producing
adaptation without selection. Have I misunderstood you?
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